Fact/Fiction: Is drinking 25 cups of coffee a day OK for your heart?

Old news, truthfully retold. This week we assess if that caffeine fix that gets you through your day at the office really is as safe as researchers have claimed

How it was told

“I can’t start the day without a cup of coffee”, “I need my caffeine fix” and “even bad coffee is better than no coffee at all”. Love them or loathe them, coffee and tea are powering offices, lunches and morning pick-me-ups across the country.

But next to nobody would stand up and say that downing cup after cup of coffee would be a good thing. Until last week.

Reports debunked the idea that coffee is bad for your heart, trashing claims that it stiffens arteries and insisting that one cup per day has the same effect as 25.

The story was covered widely in the press both in the UK and across the globe.

Take, for instance, The Guardian’s “Up to 25 cups of coffee a day safe for heart health, study finds” with similar stories in The Daily Telegraph, Metro, The Independent, The Sun and Mail Online.

The Times opted for the reassuring “Perk up, that 25th cup of coffee won’t harm your heart” while Express Online went for the SEO-heavy “Heart attack: Want to prevent the deadly condition? How much coffee you can drink a day”.

As mentioned, the story was also covered abroad, including on CNN. They went for: “Up to 25 cups of coffee a day still safe for heart health, study says”.

But are the stories true? Is it really safe to drink that much coffee every day?

Facts. Checked

It might sound far-fetched but yes, it’s true.

All the stories came from a study carried out by London’s Queen Mary University (QMU) and the British Heart Foundation.

Researchers tested 8,412 people split up into three groups: those who drink less than one cup per day, between one and three cups per day and those who down more than three cups a day.

Anybody who drank more than 25 cups per day was excluded from the study – but academics did discover that there was no arterial stiffening for people who drank up to the high limit when compared to those drinking one cup per day.

In previous studies, coffee had been associated with arterial stiffness that increases the chances of stroke or heart attack.

However, before you flick on the coffee machine, academics were clear that this isn’t just carte blanche to drink coffee to your heart’s content.

CNN were the only news outlet to speak to Dr Kenneth Fung, who led the research for QMU. He said: “We’re not telling people to drink 25 cups a day per se. If anything, if you drink within recommended guidelines then we don’t expect to see an increase in arterial stiffness compared with those who drink one cup or less a day.”

While drinking that much coffee may be OK for the heart, that’s not to say that there won’t be other effects.

London Evening Standard’s Susannah Butler tried out 25 cups on June 3 – the day that the stories went viral – and reported varying energy levels and a bad case of coffee breath.

With 95 milligrams of caffeine in each 8oz cup of brewed coffee, you would be consuming 2,375mg by drinking 25 cups, much higher than the 400mg per day (300mg per day for pregnant women) recommended by Health Canada in 2003.

The NHS doesn’t have its own guidelines but it does warn that caffeinated drinks can make the body pass urine more quickly and advises cutting down on caffeine to beat insomnia. 

So it’s probably best not to guzzle down 25 cups per day, but at least be safe in the knowledge that your heart will probably be OK.

Image: Miles Cole